/*
Copyright 2009 David Revell

This file is part of SwiFTP.

SwiFTP is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

SwiFTP is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with SwiFTP.  If not, see <http://www.gnu.org/licenses/>.
 */

package org.swiftp.server;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.util.Arrays;
import java.util.Collections;
import java.util.LinkedList;
import java.util.List;
import java.util.Queue;

import org.json.JSONException;
import org.json.JSONObject;
import org.swiftp.Defaults;
import org.swiftp.FTPServerService;
import org.swiftp.Globals;
import org.swiftp.MyLog;
import org.swiftp.R;
import org.swiftp.Util;

import android.content.Context;
import android.content.SharedPreferences;
import android.util.Log;

public class ProxyConnector extends Thread {
    public static final int IN_BUF_SIZE = 2048;
    public static final String ENCODING = "UTF-8";
    public static final int RESPONSE_WAIT_MS = 10000;
    public static final int QUEUE_WAIT_MS = 20000;
    public static final long UPDATE_USAGE_BYTES = 5000000;
    public static final String PREFERRED_SERVER = "preferred_server"; // preferences
    public static final int CONNECT_TIMEOUT = 5000;

    private final FTPServerService ftpServerService;
    private final MyLog myLog = new MyLog(getClass().getName());
    private JSONObject response = null;
    private Thread responseWaiter = null;
    private final Queue<Thread> queuedRequestThreads = new LinkedList<Thread>();
    private Socket commandSocket = null;
    private OutputStream out = null;
    private String hostname = null;
    private InputStream inputStream = null;
    private long proxyUsage = 0;
    private State proxyState = State.DISCONNECTED;
    private String prefix;
    private String proxyMessage = null;

    public enum State {
        CONNECTING, CONNECTED, FAILED, UNREACHABLE, DISCONNECTED
    };

    // QuotaStats cachedQuotaStats = null; // quotas have been canceled for now

    static final String USAGE_PREFS_NAME = "proxy_usage_data";

    /*
     * We establish a so-called "command session" to the proxy. New connections will be
     * handled by creating addition control and data connections to the proxy. See
     * proxy_protocol.txt and proxy_architecture.pdf for an explanation of how proxying
     * works. Hint: it's complicated.
     */

    public ProxyConnector(FTPServerService ftpServerService) {
        this.ftpServerService = ftpServerService;
        this.proxyUsage = getPersistedProxyUsage();
        setProxyState(State.DISCONNECTED);
        Globals.setProxyConnector(this);
    }

    @Override
    public void run() {
        myLog.i("In ProxyConnector.run()");
        setProxyState(State.CONNECTING);
        try {
            String candidateProxies[] = getProxyList();
            for (String candidateHostname : candidateProxies) {
                hostname = candidateHostname;
                commandSocket = newAuthedSocket(hostname, Defaults.REMOTE_PROXY_PORT);
                if (commandSocket == null) {
                    continue;
                }
                commandSocket.setSoTimeout(0); // 0 == forever
                // commandSocket.setKeepAlive(true);
                // Now that we have authenticated, we want to start the command session so
                // we can
                // be notified of pending control sessions.
                JSONObject request = makeJsonRequest("start_command_session");
                response = sendRequest(commandSocket, request);
                if (response == null) {
                    myLog.i("Couldn't create proxy command session");
                    continue; // try next server
                }
                if (!response.has("prefix")) {
                    myLog.l(Log.INFO,
                            "start_command_session didn't receive a prefix in response");
                    continue; // try next server
                }
                prefix = response.getString("prefix");
                response = null; // Indicate that response is free for other use
                myLog.l(Log.INFO, "Got prefix of: " + prefix);
                break; // breaking with commandSocket != null indicates success
            }
            if (commandSocket == null) {
                myLog.l(Log.INFO, "No proxies accepted connection, failing.");
                setProxyState(State.UNREACHABLE);
                return;
            }
            setProxyState(State.CONNECTED);
            preferServer(hostname);
            inputStream = commandSocket.getInputStream();
            out = commandSocket.getOutputStream();
            int numBytes;
            byte[] bytes = new byte[IN_BUF_SIZE];
            // spawnQuotaRequester().start();
            while (true) {
                myLog.d("to proxy read()");
                numBytes = inputStream.read(bytes);
                incrementProxyUsage(numBytes);
                myLog.d("from proxy read()");
                JSONObject incomingJson = null;
                if (numBytes > 0) {
                    String responseString = new String(bytes, ENCODING);
                    incomingJson = new JSONObject(responseString);
                    if (incomingJson.has("action")) {
                        // If the incoming JSON object has an "action" field, then it is a
                        // request, and not a response
                        incomingCommand(incomingJson);
                    } else {
                        // If the incoming JSON object does not have an "action" field,
                        // then
                        // it is a response to a request we sent earlier.
                        // If there's an object waiting for a response, then that object
                        // will be referenced by responseWaiter.
                        if (responseWaiter != null) {
                            if (response != null) {
                                myLog.l(Log.INFO,
                                        "Overwriting existing cmd session response");
                            }
                            response = incomingJson;
                            responseWaiter.interrupt();
                        } else {
                            myLog.l(Log.INFO, "Response received but no responseWaiter");
                        }
                    }
                } else if (numBytes == 0) {
                    myLog.d("Command socket read 0 bytes, looping");
                } else { // numBytes < 0
                    myLog.l(Log.DEBUG, "Command socket end of stream, exiting");
                    if (proxyState != State.DISCONNECTED) {
                        // Set state to FAILED unless this was an intentional
                        // socket closure.
                        setProxyState(State.FAILED);
                    }
                    break;
                }
            }
            myLog.l(Log.INFO, "ProxyConnector thread quitting cleanly");
        } catch (IOException e) {
            myLog.l(Log.INFO, "IOException in command session: " + e);
            setProxyState(State.FAILED);
        } catch (JSONException e) {
            myLog.l(Log.INFO, "Commmand socket JSONException: " + e);
            setProxyState(State.FAILED);
        } catch (Exception e) {
            myLog.l(Log.INFO, "Other exception in ProxyConnector: " + e);
            setProxyState(State.FAILED);
        } finally {
            Globals.setProxyConnector(null);
            hostname = null;
            myLog.d("ProxyConnector.run() returning");
            persistProxyUsage();
        }
    }

    // This function is used to spawn a new Thread that will make a request over the
    // command thread. Since the main ProxyConnector thread handles the input
    // request/response de-multiplexing, it cannot also make a request using the
    // sendCmdSocketRequest, since sendCmdSocketRequest will block waiting for
    // a response, but the same thread is expected to deliver the response.
    // The short story is, if the main ProxyConnector command session thread wants to
    // make a request, the easiest way is to spawn a new thread and have it call
    // sendCmdSocketRequest in the same way as any other thread.
    // private Thread spawnQuotaRequester() {
    // return new Thread() {
    // public void run() {
    // getQuotaStats(false);
    // }
    // };
    // }

    /**
     * Since we want devices to generally stick with the same proxy server, and we may
     * want to explicitly redirect some devices to other servers, we have this mechanism
     * to store a "preferred server" on the device.
     */
    private void preferServer(String hostname) {
        SharedPreferences prefs = Globals.getContext().getSharedPreferences(
                PREFERRED_SERVER, 0);
        SharedPreferences.Editor editor = prefs.edit();
        editor.putString(PREFERRED_SERVER, hostname);
        editor.commit();
    }

    private String[] getProxyList() {
        SharedPreferences prefs = Globals.getContext().getSharedPreferences(
                PREFERRED_SERVER, 0);
        String preferred = prefs.getString(PREFERRED_SERVER, null);

        String[] allProxies;

        if (Defaults.release) {
            allProxies = new String[] { "c1.swiftp.org", "c2.swiftp.org",
                    "c3.swiftp.org", "c4.swiftp.org", "c5.swiftp.org", "c6.swiftp.org",
                    "c7.swiftp.org", "c8.swiftp.org", "c9.swiftp.org" };
        } else {
            // allProxies = new String[] {
            // "cdev.swiftp.org"
            // };
            allProxies = new String[] { "c1.swiftp.org", "c2.swiftp.org",
                    "c3.swiftp.org", "c4.swiftp.org", "c5.swiftp.org", "c6.swiftp.org",
                    "c7.swiftp.org", "c8.swiftp.org", "c9.swiftp.org" };
        }

        // We should randomly permute the server list in order to spread
        // load between servers. Collections offers a shuffle() function
        // that does this, so we'll convert to List and back to String[].
        List<String> proxyList = Arrays.asList(allProxies);
        Collections.shuffle(proxyList);
        allProxies = proxyList.toArray(new String[] {}); // arg used for type

        // Return preferred server first, followed by all others
        if (preferred == null) {
            return allProxies;
        } else {
            return Util.concatStrArrays(new String[] { preferred }, allProxies);
        }
    }

    private boolean checkAndPrintJsonError(JSONObject json) throws JSONException {
        if (json.has("error_code")) {
            // The returned JSON object will have a field called "errorCode"
            // if there was a problem executing our request.
            StringBuilder s = new StringBuilder("Error in JSON response, code: ");
            s.append(json.getString("error_code"));
            if (json.has("error_string")) {
                s.append(", string: ");
                s.append(json.getString("error_string"));
            }
            myLog.l(Log.INFO, s.toString());

            // Obsolete: there's no authentication anymore
            // Dev code to enable frequent database wipes. If we fail to login,
            // remove our stored account info, causing a create_account action
            // next time.
            // if(!Defaults.release) {
            // if(json.getInt("error_code") == 11) {
            // myLog.l(Log.DEBUG, "Dev: removing secret due to login failure");
            // removeSecret();
            // }
            // }
            return true;
        }
        return false;
    }

    /**
     * Reads our persistent storage, looking for a stored proxy authentication secret.
     * 
     * @return The secret, if present, or null.
     */
    // Obsolete, there's no authentication anymore
    /*
     * private String retrieveSecret() { SharedPreferences settings =
     * Globals.getContext(). getSharedPreferences(Defaults.getSettingsName(),
     * Defaults.getSettingsMode()); return settings.getString("proxySecret", null); }
     */

    // Obsolete, there's no authentication anymore
    /*
     * private void storeSecret(String secret) { SharedPreferences settings =
     * Globals.getContext(). getSharedPreferences(Defaults.getSettingsName(),
     * Defaults.getSettingsMode()); Editor editor = settings.edit();
     * editor.putString("proxySecret", secret); editor.commit(); }
     */

    // Obsolete, there's no authentication anymore
    /*
     * private void removeSecret() { SharedPreferences settings = Globals.getContext().
     * getSharedPreferences(Defaults.getSettingsName(), Defaults.getSettingsMode());
     * Editor editor = settings.edit(); editor.remove("proxySecret"); editor.commit(); }
     */

    private void incomingCommand(JSONObject json) {
        try {
            String action = json.getString("action");
            if (action.equals("control_connection_waiting")) {
                startControlSession(json.getInt("port"));
            } else if (action.equals("prefer_server")) {
                String host = json.getString("host"); // throws JSONException, fine
                preferServer(host);
                myLog.i("New preferred server: " + host);
            } else if (action.equals("message")) {
                proxyMessage = json.getString("text");
                myLog.i("Got news from proxy server: \"" + proxyMessage + "\"");
                // TODO: send intent to notify UI about news
                // FTPServerService.updateClients(); // UI update to show message
            } else if (action.equals("noop")) {
                myLog.d("Proxy noop");
            } else {
                myLog.l(Log.INFO, "Unsupported incoming action: " + action);
            }
            // If we're starting a control session register with ftpServerService
        } catch (JSONException e) {
            myLog.l(Log.INFO, "JSONException in proxy incomingCommand");
        }
    }

    private void startControlSession(int port) {
        Socket socket;
        myLog.d("Starting new proxy FTP control session");
        socket = newAuthedSocket(hostname, port);
        if (socket == null) {
            myLog.i("startControlSession got null authed socket");
            return;
        }
        ProxyDataSocketFactory dataSocketFactory = new ProxyDataSocketFactory();
        SessionThread thread = new SessionThread(socket, dataSocketFactory,
                SessionThread.Source.PROXY);
        thread.start();
        ftpServerService.registerSessionThread(thread);
    }

    /**
     * Connects an outgoing socket to the proxy and authenticates, creating an account if
     * necessary.
     */
    private Socket newAuthedSocket(String hostname, int port) {
        if (hostname == null) {
            myLog.i("newAuthedSocket can't connect to null host");
            return null;
        }
        JSONObject json = new JSONObject();
        // String secret = retrieveSecret();
        Socket socket;
        OutputStream out = null;
        InputStream in = null;

        try {
            myLog.d("Opening proxy connection to " + hostname + ":" + port);
            socket = new Socket();
            socket.connect(new InetSocketAddress(hostname, port), CONNECT_TIMEOUT);
            json.put("android_id", Util.getAndroidId());
            json.put("swiftp_version", Util.getVersion());
            json.put("action", "login");
            out = socket.getOutputStream();
            in = socket.getInputStream();
            int numBytes;

            out.write(json.toString().getBytes(ENCODING));
            myLog.l(Log.DEBUG, "Sent login request");
            // Read and parse the server's response
            byte[] bytes = new byte[IN_BUF_SIZE];
            // Here we assume that the server's response will all be contained in
            // a single read, which may be unsafe for large responses
            numBytes = in.read(bytes);
            if (numBytes == -1) {
                myLog.l(Log.INFO, "Proxy socket closed while waiting for auth response");
                return null;
            } else if (numBytes == 0) {
                myLog.l(Log.INFO, "Short network read waiting for auth, quitting");
                return null;
            }
            json = new JSONObject(new String(bytes, 0, numBytes, ENCODING));
            if (checkAndPrintJsonError(json)) {
                return null;
            }
            myLog.d("newAuthedSocket successful");
            return socket;
        } catch (Exception e) {
            myLog.i("Exception during proxy connection or authentication: " + e);
            return null;
        }
    }

    public void quit() {
        setProxyState(State.DISCONNECTED);
        try {
            sendRequest(commandSocket, makeJsonRequest("finished")); // ignore reply

            if (inputStream != null) {
                myLog.d("quit() closing proxy inputStream");
                inputStream.close();
            } else {
                myLog.d("quit() won't close null inputStream");
            }
            if (commandSocket != null) {
                myLog.d("quit() closing proxy socket");
                commandSocket.close();
            } else {
                myLog.d("quit() won't close null socket");
            }
        } catch (IOException e) {
        } catch (JSONException e) {
        }
        persistProxyUsage();
        Globals.setProxyConnector(null);
    }

    @SuppressWarnings("unused")
	private JSONObject sendCmdSocketRequest(JSONObject json) {
        try {
            boolean queued;
            synchronized (this) {
                if (responseWaiter == null) {
                    responseWaiter = Thread.currentThread();
                    queued = false;
                    myLog.d("sendCmdSocketRequest proceeding without queue");
                } else if (!responseWaiter.isAlive()) {
                    // This code should never run. It is meant to recover from a situation
                    // where there is a thread that sent a proxy request but died before
                    // starting the subsequent request. If this is the case, the correct
                    // behavior is to run the next queued thread in the queue, or if the
                    // queue is empty, to perform our own request.
                    myLog.l(Log.INFO, "Won't wait on dead responseWaiter");
                    if (queuedRequestThreads.size() == 0) {
                        responseWaiter = Thread.currentThread();
                        queued = false;
                    } else {
                        queuedRequestThreads.add(Thread.currentThread());
                        queuedRequestThreads.remove().interrupt(); // start queued thread
                        queued = true;
                    }
                } else {
                    myLog.d("sendCmdSocketRequest queueing thread");
                    queuedRequestThreads.add(Thread.currentThread());
                    queued = true;
                }
            }
            // If a different thread has sent a request and is waiting for a response,
            // then the current thread will be in a queue waiting for an interrupt
            if (queued) {
                // The current thread must wait until we are popped off the waiting queue
                // and receive an interrupt()
                boolean interrupted = false;
                try {
                    myLog.d("Queued cmd session request thread sleeping...");
                    Thread.sleep(QUEUE_WAIT_MS);
                } catch (InterruptedException e) {
                    myLog.l(Log.DEBUG, "Proxy request popped and ready");
                    interrupted = true;
                }
                if (!interrupted) {
                    myLog.l(Log.INFO, "Timed out waiting on proxy queue");
                    return null;
                }
            }
            // We have been popped from the wait queue if necessary, and now it's time
            // to send the request.
            try {
                responseWaiter = Thread.currentThread();
                byte[] outboundData = Util.jsonToByteArray(json);
                try {
                    out.write(outboundData);
                } catch (IOException e) {
                    myLog.l(Log.INFO, "IOException sending proxy request");
                    return null;
                }
                // Wait RESPONSE_WAIT_MS for a response from the proxy
                boolean interrupted = false;
                try {
                    // Wait for the main ProxyConnector thread to interrupt us, meaning
                    // that a response has been received.
                    myLog.d("Cmd session request sleeping until response");
                    Thread.sleep(RESPONSE_WAIT_MS);
                } catch (InterruptedException e) {
                    myLog.d("Cmd session response received");
                    interrupted = true;
                }
                if (!interrupted) {
                    myLog.l(Log.INFO, "Proxy request timed out");
                    return null;
                }
                // At this point, the main ProxyConnector thread will have stored
                // our response in "JSONObject response".
                myLog.d("Cmd session response was: " + response);
                return response;
            } finally {
                // Make sure that when this request finishes, the next thread on the
                // queue gets started.
                synchronized (this) {
                    if (queuedRequestThreads.size() != 0) {
                        queuedRequestThreads.remove().interrupt();
                    }
                }
            }
        } catch (JSONException e) {
            myLog.l(Log.INFO, "JSONException in sendRequest: " + e);
            return null;
        }
    }

    public JSONObject sendRequest(InputStream in, OutputStream out, JSONObject request)
            throws JSONException {
        try {
            out.write(Util.jsonToByteArray(request));
            byte[] bytes = new byte[IN_BUF_SIZE];
            int numBytes = in.read(bytes);
            if (numBytes < 1) {
                myLog.i("Proxy sendRequest short read on response");
                return null;
            }
            JSONObject response = Util.byteArrayToJson(bytes);
            if (response == null) {
                myLog.i("Null response to sendRequest");
            }
            if (checkAndPrintJsonError(response)) {
                myLog.i("Error response to sendRequest");
                return null;
            }
            return response;
        } catch (IOException e) {
            myLog.i("IOException in proxy sendRequest: " + e);
            return null;
        }
    }

    public JSONObject sendRequest(Socket socket, JSONObject request) throws JSONException {
        try {
            if (socket == null) {
                // The server is probably shutting down
                myLog.i("null socket in ProxyConnector.sendRequest()");
                return null;
            } else {
                return sendRequest(socket.getInputStream(), socket.getOutputStream(),
                        request);
            }
        } catch (IOException e) {
            myLog.i("IOException in proxy sendRequest wrapper: " + e);
            return null;
        }
    }

    public ProxyDataSocketInfo pasvListen() {
        try {
            // connect to proxy and authenticate
            myLog.d("Sending data_pasv_listen to proxy");
            Socket socket = newAuthedSocket(this.hostname, Defaults.REMOTE_PROXY_PORT);
            if (socket == null) {
                myLog.i("pasvListen got null socket");
                return null;
            }
            JSONObject request = makeJsonRequest("data_pasv_listen");

            JSONObject response = sendRequest(socket, request);
            if (response == null) {
                return null;
            }
            int port = response.getInt("port");
            return new ProxyDataSocketInfo(socket, port);
        } catch (JSONException e) {
            myLog.l(Log.INFO, "JSONException in pasvListen");
            return null;
        }
    }

    public Socket dataPortConnect(InetAddress clientAddr, int clientPort) {
        /**
         * This function is called by a ProxyDataSocketFactory when it's time to transfer
         * some data in PORT mode (not PASV mode). We send a data_port_connect request to
         * the proxy, containing the IP and port of the FTP client to which a connection
         * should be made.
         */
        try {
            myLog.d("Sending data_port_connect to proxy");
            Socket socket = newAuthedSocket(this.hostname, Defaults.REMOTE_PROXY_PORT);
            if (socket == null) {
                myLog.i("dataPortConnect got null socket");
                return null;
            }
            JSONObject request = makeJsonRequest("data_port_connect");
            request.put("address", clientAddr.getHostAddress());
            request.put("port", clientPort);
            JSONObject response = sendRequest(socket, request);
            if (response == null) {
                return null; // logged elsewhere
            }
            return socket;
        } catch (JSONException e) {
            myLog.i("JSONException in dataPortConnect");
            return null;
        }
    }

    /**
     * Given a socket returned from pasvListen(), send a data_pasv_accept request over the
     * socket to the proxy, which should result in a socket that is ready for data
     * transfer with the FTP client. Of course, this will only work if the FTP client
     * connects to the proxy like it's supposed to. The client will have already been told
     * to connect by the response to its PASV command.
     * 
     * This should only be called from the onTransfer method of ProxyDataSocketFactory.
     * 
     * @param socket
     *            A socket previously returned from ProxyConnector.pasvListen()
     * @return true if the accept operation completed OK, otherwise false
     */

    public boolean pasvAccept(Socket socket) {
        try {
            JSONObject request = makeJsonRequest("data_pasv_accept");
            JSONObject response = sendRequest(socket, request);
            if (response == null) {
                return false; // error is logged elsewhere
            }
            if (checkAndPrintJsonError(response)) {
                myLog.i("Error response to data_pasv_accept");
                return false;
            }
            // The proxy's response will be an empty JSON object on success
            myLog.d("Proxy data_pasv_accept successful");
            return true;
        } catch (JSONException e) {
            myLog.i("JSONException in pasvAccept: " + e);
            return false;
        }
    }

    public InetAddress getProxyIp() {
        if (this.isAlive()) {
            if (commandSocket.isConnected()) {
                return commandSocket.getInetAddress();
            }
        }
        return null;
    }

    private JSONObject makeJsonRequest(String action) throws JSONException {
        JSONObject json = new JSONObject();
        json.put("action", action);
        return json;
    }

    /*
     * Quotas have been canceled for now public QuotaStats getQuotaStats(boolean
     * canUseCached) { if(canUseCached) { if(cachedQuotaStats != null) {
     * myLog.d("Returning cachedQuotaStats"); return cachedQuotaStats; } else {
     * myLog.d("Would return cached quota stats but none retrieved"); } } // If there's no
     * cached quota stats, or if the called wants fresh stats, // make a JSON request to
     * the proxy, assuming the command session is open. try { JSONObject response =
     * sendCmdSocketRequest(makeJsonRequest("check_quota")); int used, quota; if(response
     * == null) { myLog.w("check_quota got null response"); return null; } used =
     * response.getInt("used"); quota = response.getInt("quota");
     * myLog.d("Got quota response of " + used + "/" + quota); cachedQuotaStats = new
     * QuotaStats(used, quota) ; return cachedQuotaStats; } catch (JSONException e) {
     * myLog.w("JSONException in getQuota: " + e); return null; } }
     */

    // We want to track the total amount of data sent via the proxy server, to
    // show it to the user and encourage them to donate.
    void persistProxyUsage() {
        if (proxyUsage == 0) {
            return; // This shouldn't happen, but just for safety
        }
        SharedPreferences prefs = Globals.getContext().getSharedPreferences(
                USAGE_PREFS_NAME, 0); // 0 == private
        SharedPreferences.Editor editor = prefs.edit();
        editor.putLong(USAGE_PREFS_NAME, proxyUsage);
        editor.commit();
        myLog.d("Persisted proxy usage to preferences");
    }

    long getPersistedProxyUsage() {
        // This gets the last persisted value for bytes transferred through
        // the proxy. It can be out of date since it doesn't include data
        // transferred during the current session.
        SharedPreferences prefs = Globals.getContext().getSharedPreferences(
                USAGE_PREFS_NAME, 0); // 0 == private
        return prefs.getLong(USAGE_PREFS_NAME, 0); // Default count of 0
    }

    long getProxyUsage() {
        // This gets the running total of all proxy usage, which may not have
        // been persisted yet.
        return proxyUsage;
    }

    void incrementProxyUsage(long num) {
        long oldProxyUsage = proxyUsage;
        proxyUsage += num;
        if (proxyUsage % UPDATE_USAGE_BYTES < oldProxyUsage % UPDATE_USAGE_BYTES) {
            // TODO: Use intent to update UI
            // FTPServerService.updateClients();
            persistProxyUsage();
        }
    }

    public State getProxyState() {
        return proxyState;
    }

    private void setProxyState(State state) {
        proxyState = state;
        myLog.l(Log.DEBUG, "Proxy state changed to " + state, true);
        // TODO: Use intent to update UI
        // FTPServerService.updateClients();
    }

    static public String stateToString(State s) {
        Context ctx = Globals.getContext();
        switch (s) {
        case DISCONNECTED:
            return ctx.getString(R.string.pst_disconnected);
        case CONNECTING:
            return ctx.getString(R.string.pst_connecting);
        case CONNECTED:
            return ctx.getString(R.string.pst_connected);
        case FAILED:
            return ctx.getString(R.string.pst_failed);
        case UNREACHABLE:
            return ctx.getString(R.string.pst_unreachable);
        default:
            return ctx.getString(R.string.unknown);
        }
    }

    /**
     * The URL to which users should point their FTP client.
     */
    public String getURL() {
        if (proxyState == State.CONNECTED) {
            String username = Globals.getUsername();
            if (username != null) {
                return "ftp://" + prefix + "_" + username + "@" + hostname;
            }
        }
        return Globals.getContext().getString(R.string.unknown);
    }

    /**
     * If the proxy sends a human-readable message, it can be retrieved by calling this
     * function. Returns null if no message has been received.
     */
    public String getProxyMessage() {
        return proxyMessage;
    }

}
